Leaking NPT threaded connection help

[kinetic]

I got a 55g water tank (Ace Roto: https://www.ruralking.com/ace-roto-mold-55-gallon-vertical-dome-top-vt0055-20.html) to hold RO/DI water. It came with a bulkhead with a threaded Female NPT.

I went to Home Depot and got a male NPT to slip converter, and put on a spare union ballhead that I had laying around.

Unfortunately, I have a super slow leak from the threads between bulkhead and the MPT > Slip fitting. It drips probably once every 10 minutes or so. I actually stood there for 10 minutes and didn't see much happen, but I think a new drop of water came off of it, who knows. There's a constant wet spot and I can see a small bit of water collect on the plumbing.

I threaded it as far in as I could. I tried using some plumbers tape, but that didn't work either. Any ideas?

Things I'm thinking of trying
1. Use plumber cement (is this safe?)
2. Use silicon on the threads and rethread it in
3. Replacing the bulkhead with a slip bulkhead instead of threaded (somehow, not sure how I can get my hand all the way into this tank to put it together)

Any other ideas?

 

[Coral reefer]

You use some teflon tape? 3 layers?
I often use "liquid teflon" from hardware store.

 

[rygh]

I use silicone on all threaded connections.
Seals great, and you can take them apart easier.
BUT:
Let it dry overnight before getting wet.
Don't use it if there is a chance you may partially unscrew it. Doing that rips it apart, and you can get a leak.

 

[kinetic]

You use some teflon tape? 3 layers?
I often use "liquid teflon" from hardware store.

I always assumed teflon was for metal threaded fittings? I've used them on PVC before, and people thought I was weird. I have a ton of it left, so maybe I'll try that!

I use silicone on all threaded connections.
Seals great, and you can take them apart easier.
BUT:
Let it dry overnight before getting wet.
Don't use it if there is a chance you may partially unscrew it. Doing that rips it apart, and you can get a leak.

OK that's good to know. I'll try this next if the 3 layers of teflon tape doesn't work.

Last question: is it common for NPT threads like this to leak without silicon/teflon?

 

[sfsuphysics]

Yeah, plumbers paste instead of tape

 

[Yippee]

I am using Rectorseal T Plus 2. For metal and plastic pipe threads.

 

[xcaret]

What both Mikes suggest, just make sure is the safe for drinking water or teflon tape. Do not over tighten or you may break the bulkhead.

 

[iani]

Tape will work fine. Make sure you wrap the tape clockwise.

 

[Wlachnit]

I'm a Rectorseal user as well. I've also been told that the Teflon tape isn't meant for PVC pipe.


Sent from my iPad using Tapatalk

 

[daddio]

Are you sure it is not coming from the barrel? Put the rubber seal on the inside where it belongs?

 

[RandyC]

https://www.linkedin.com/pulse/what-thread-sealant-use-pvc-fittings-larry-workman

 

[Yippee]

Formulated for drinking water.

 

[kinetic]

Are you sure it is not coming from the barrel? Put the rubber seal on the inside where it belongs?

Yes it's not coming from the tank itself. The rubber seal is on the inside already.

Formulated for drinking water. View attachment 8080 View attachment 8081

Oh good! I'll probably skip Teflon tape and just goto Ace hardware to find RectorSeal.

 

[Coral reefer]

That's what I meant by liquid teflon